KVM: s390: fix sigp set prefix status stored cases

If an invalid parameter is passed or the addressed cpu is in an
incorrect state sigp set prefix will store a status.
This status must only have bits set as defined by the architecture.
The current kvm implementation missed to clear bits and also did
not set the intended status bit ("and" instead of "or" operation).
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

arch/s390/kvm/sigp.c

@@ -207,6 +207,7 @@ static int __sigp_set_prefix(struct kvm_vcpu *vcpu, u16 cpu_addr, u32 address,
 	address = address & 0x7fffe000u;
 	if (copy_from_guest_absolute(vcpu, &tmp, address, 1) ||
 	   copy_from_guest_absolute(vcpu, &tmp, address + PAGE_SIZE, 1)) {
+		*reg &= 0xffffffff00000000UL;
 		*reg |= SIGP_STATUS_INVALID_PARAMETER;
 		return 1; /* invalid parameter */
 	}
@@ -220,8 +221,9 @@ static int __sigp_set_prefix(struct kvm_vcpu *vcpu, u16 cpu_addr, u32 address,
 		li = fi->local_int[cpu_addr];
 
 	if (li == NULL) {
+		*reg &= 0xffffffff00000000UL;
+		*reg |= SIGP_STATUS_INCORRECT_STATE;
 		rc = 1; /* incorrect state */
-		*reg &= SIGP_STATUS_INCORRECT_STATE;
 		kfree(inti);
 		goto out_fi;
 	}
@@ -229,8 +231,9 @@ static int __sigp_set_prefix(struct kvm_vcpu *vcpu, u16 cpu_addr, u32 address,
 	spin_lock_bh(&li->lock);
 	/* cpu must be in stopped state */
 	if (!(atomic_read(li->cpuflags) & CPUSTAT_STOPPED)) {
+		*reg &= 0xffffffff00000000UL;
+		*reg |= SIGP_STATUS_INCORRECT_STATE;
 		rc = 1; /* incorrect state */
-		*reg &= SIGP_STATUS_INCORRECT_STATE;
 		kfree(inti);
 		goto out_li;
 	}